Surgical instrument for dispensing a fluid

ABSTRACT

A surgical instrument for dispensing a fluid includes a housing and a dispensing shaft, which is elongate and which has a proximal end and a distal end. The proximal end of the dispensing shaft is received in the housing and the distal end defines a dispensing opening for dispensing the fluid. The dispensing shaft includes a through bore which extends along the dispensing shaft from the proximal end to the dispensing opening at the distal end. The instrument further includes a dispensing assembly and a priming assembly connected to the housing which is operable to move an amount of the fluid into the through bore of the dispensing shaft to prime the through bore with the fluid before the dispensing assembly is operated.

The present invention relates to a surgical instrument for dispensing afluid. In particular the invention may relate to a surgical instrumentfor dispensing a fluid to an operative site in the human or animal body.

Surgical instruments for dispensing fluid to an operative site in thehuman or animal body are known.

WO2009/132331 discloses a minimally invasive (e.g. laparoscopic)applicator device which dispenses fluid and which may include aratcheted trigger system to overcome backflow. WO02/064192 discloses alaparoscopic gel applicator. However, it has been recognised by theapplicant that the devices disclosed in these documents do not provideany means to reduce the likelihood of accidental operation of the devicebefore the device is intended to be used.

The present invention seeks to reduce the likelihood of accidentaldispensing of fluid from a surgical instrument for dispensing a fluid.

Accordingly, the present invention provides a surgical instrument fordispensing a fluid which includes a dispensing shaft, a dispensingassembly and a priming assembly operable to prime the dispensing shaftwith the fluid before the dispensing assembly is operated.

Thus viewed from one aspect the present invention provides a surgicalinstrument for dispensing a fluid comprising:

-   -   a housing;    -   a dispensing shaft which is elongate and which has a proximal        end and a distal end, wherein the proximal end of the dispensing        shaft is received in the housing and the distal end defines a        dispensing opening for dispensing the fluid and the dispensing        shaft includes a through bore which extends along the dispensing        shaft from the proximal end to the dispensing opening at the        distal end;    -   a dispensing assembly connected to the housing which includes a        dispensing chamber which holds the fluid before it is dispensed,        wherein the dispensing chamber is in fluid communication with        the through bore of the dispensing shaft and the dispensing        assembly is operable to move the fluid from the dispensing        chamber along the through bore and dispense the fluid from the        dispensing opening; and    -   a priming assembly connected to the housing which is operable to        move an amount of the fluid into the through bore of the        dispensing shaft to prime the through bore with the fluid before        the dispensing assembly is operated.

By providing a priming assembly, the likelihood of accidental dispensingof fluid by a user of the surgical instrument may be reduced because thefluid will not be present in the through bore until the priming assemblyis operated to prime the through bore with the fluid. In this wayoperation of the dispensing assembly will not dispense fluid from thedispensing opening until the priming assembly has been operated.Reducing the likelihood of accidental dispensing of fluid isadvantageous because fluid may be dispensed in an undesirable location.For example, if the fluid is an adhesive, accidentally dispensedadhesive may contact unintended tissue in the human or animal body whichmay be undesirable.

Operation of the priming assembly may prepare the surgical instrumentfor use.

The housing may comprise a handle. The handle may allow the surgicalinstrument to be gripped in one hand to allow one-handed operation ofthe surgical instrument. The housing may comprise a body. The dispensingshaft may extend from the body. The housing may have a ‘pistol’configuration in which the handle extends from the body in a similarconfiguration to a pistol handle extending from a pistol barrel.

The dispensing shaft is elongate and has a proximal end and a distalend. The proximal end of the dispensing shaft is received within thehousing and the distal end defines a dispensing opening for dispensingthe fluid. The dispensing shaft may have a longitudinal axis. Thelongitudinal axis of the dispensing shaft may define a proximo-distalaxis for the surgical instrument. The proximo-distal axis may beoriented so that the distal direction is generally towards the distalend of the dispensing shaft and the proximal direction is generally awayfrom the distal end.

The dispensing shaft may comprise an inner tube and an outer tube. Theouter tube may be made of metal. The inner tube may be made of apolymer. The polymer may be polytetrafluoroethylene (PTFE), fluorinatedethylene propylene (FEP) or silicone. The polymer may be a non-stick orlow friction polymer. This may assist the movement of the fluid alongthe through bore by reducing shear stress. For example, when the fluidis an adhesive or has a significant viscosity, a non-stick or lowfriction polymer may assist the flow of the fluid along the throughbore.

The through bore may extend within the inner tube.

The dispensing assembly comprises a dispensing chamber. The fluid may beheld in the dispensing chamber before it is moved into the dispensingshaft to be dispensed. An elongate plunger may be positioned to advanceor retract within the dispensing chamber. When the plunger is advancedwithin the dispensing chamber, the fluid may be urged out of thedispensing chamber and into the dispensing shaft. The plunger mayadvance within the dispensing chamber in a distal direction. Fluid urgedout of the dispensing chamber may enter the through bore of thedispensing shaft at the proximal end of the dispensing shaft.

The plunger may engage the internal surface of the dispensing chamber toform a seal. Alternatively the plunger may abut against a sealing discwhich engages the internal surface of the dispensing chamber to form aseal. Advancement of the plunger may advance the sealing disc within thechamber. The plunger may include a proximal end and a distal end. Thedistal end of the plunger may abut the sealing disc.

Preferably the plunger abuts against a sealing disc which is slidablymounted within the dispensing chamber, wherein operation of thedispensing assembly causes the plunger to advance the sealing discwithin the dispensing chamber to urge the fluid out of the dispensingchamber and along the through bore in the dispensing shaft.

The plunger may be connected to a plunger drive assembly. The plungerdrive assembly may be a rack and pinion. The pinion gear wheel may bemounted within the housing. Turning the pinion gear wheel may engage therack to advance or retract the plunger along the dispensing chamber.

The dispensing assembly may comprise a dispensing actuator. Thedispensing actuator may be operable to drive the dispensing assembly.The dispensing actuator may be reciprocable between a first dispensingposition and a second dispensing position. Movement of the dispensingactuator from the first dispensing position to the second dispensingposition may advance the plunger and urge fluid out of the dispensingchamber and along the dispensing shaft. The dispensing actuator may bebiased to return to the first dispensing position when it is released atthe second dispensing position.

The dispensing actuator may be connected to the plunger drive assembly.For example, the dispensing actuator may be connected by an intermediategear wheel to the pinion gear of the plunger drive assembly.

The dispensing actuator may be a trigger. The trigger may bereciprocable. The trigger may be mounted to the housing. The trigger maybe mounted on the handle or the body of the housing. The trigger may beoperable by a user's finger from a first trigger position to a secondtrigger position. The trigger may be biased by a spring to return to thefirst trigger position when the user's finger is released at the secondtrigger position. The spring may be attached to the housing at a firstend and attached to the trigger at a second end.

Preferably the dispensing assembly includes a trigger mounted to thehousing which is operable to dispense a predetermined amount of fluideach time the trigger is operated.

A pawl and ratchet may be connected to the trigger and a trigger gearwheel. The pawl may be connected to one of the trigger or the triggergear wheel and the ratchet may be connected to the other of the triggeror the trigger gear wheel. The pawl may be moulded into the trigger.When the trigger is moved from the first trigger position to the secondtrigger position the pawl may engage the ratchet to turn the triggergear wheel. When the trigger is moved from the second trigger positionto the first trigger position the pawl and ratchet may disengage so thatthe trigger gear wheel does not turn.

Turning the trigger gear wheel may turn the pinion gear wheel to advancethe plunger. An intermediate gear wheel may be connected between thetrigger gear wheel and the pinion gear wheel. The relative sizes of thetrigger gear wheel and pinion gear wheel may be chosen to provide asuitable gear reduction. This may provide a mechanical advantage to theoperation of the trigger from the first trigger position to the secondtrigger position. The intermediate gear may contribute to the gearreduction. The overall gear ratio between the trigger gear wheel and thepinion gear wheel may be 4 to 1. Therefore a 10° rotation of the triggermay result in a 2.5° rotation of the pinion gear wheel. The size of thepinion gear wheel may be chosen to advance the rack by a predeterminedamount when the trigger is operated from the first trigger position tothe second trigger position. This will cause the plunger to advance by apredetermined amount to dispense a predetermined volume of the fluid.

An indexing wheel may be attached to the trigger gear wheel. Theindexing wheel may enable the movement of the trigger between the firsttrigger position and the second trigger position to be indexed. Theindexing wheel may include indentations on its circumference whichengage an indexing formation on the housing to provide the indexing. Theengagement of the indentations with the indexing formation may alsoprovide an additional frictional force on the ratchet to assist thetrigger to move from the second trigger position to the first triggerposition without moving the ratchet.

The priming assembly may comprise a priming actuator. The primingactuator may be operable to drive the priming assembly. The primingactuator may be mounted to a proximal end of the housing. The primingactuator may be rotatably mounted to the housing. The priming actuatormay be operable from a first priming position to a second primingposition. The priming actuator may be rotatable from the first primingposition to the second priming position.

The priming assembly may include a safety element which is moveable froman engaged position to a disengaged position. The safety element mayprevent the priming assembly from being operated when it is in theengaged position. The safety element may be in the form of a pull tabconnected to the priming actuator. In its engaged position, the pull tabmay engage a recess on the housing to prevent the priming actuator frombeing operated from the first priming position to the second primingposition. The pull tab may be separable from the priming actuator sothat in its disengaged position, the pull tab is separated from thepriming actuator and disengaged from the recess so that the primingactuator can be operated.

Preferably the priming assembly includes a safety element which ismoveable from an engaged position to a disengaged position, wherein whensafety element is in the engaged position it prevents the primingassembly from being operated and when the safety element is in thedisengaged position the priming assembly is operable.

Operation of the priming actuator may cause the plunger to advance intothe dispensing chamber. The plunger may advance in a distal direction.

If the priming actuator is rotatably mounted to the housing, rotation ofthe priming actuator may rotate a priming cap with an internal screwthread. The priming cap may be linearly moveable with respect to thepriming actuator by the engagement of a spline feature on one of thepriming cap or the priming actuator with a groove on the other of thepriming cap or priming actuator. The internal screw thread on thepriming cap may engage a complementary screw thread mounted on theplunger drive assembly. The priming cap may be connected to the proximalend of the plunger. In this way, rotation of the priming actuator maycause the internal screw thread on the priming cap to advance along thecomplementary screw thread on the plunger drive assembly. Since theplunger is connected to the priming cap, the plunger will advancedistally with respect to the plunger drive assembly. The advancement ofthe plunger may prime the through bore of the dispensing shaft withfluid by advancing the sealing disc in the dispensing chamber and urgingthe fluid out of the dispensing chamber.

Preferably, the priming assembly and the dispensing assembly form aninterlock so that the dispensing assembly cannot be operated until thepriming assembly has been operated. The interlock may be moveable from alocked configuration in which it prevents the dispensing assembly frombeing operated to a released configuration in which the dispensingassembly is operable. The interlock may only be moveable to the releasedconfiguration once the priming actuator is in the second primingposition. An advantage of the interlock may be that accidental operationof the dispensing assembly is not possible until the priming assemblyhas been operated and the priming actuator is in the second primingposition.

The interlock may include a locking member. The locking member may beelongate and may be moveably mounted in the housing to contact a lockingformation on the dispensing assembly and to contact the primingactuator. When the priming actuator is in the first priming position andthe interlock is in the locked configuration, the locking member may beunable to move and may lock the trigger in the second trigger positionby contact with the locking formation.

The priming actuator may include an interlock recess positioned so thatwhen the priming actuator is in the second priming position, theinterlock recess is aligned with the locking member to allow the lockingmember to move into the interlock recess. The spring bias on the triggermay then cause the locking formation to move the locking member into theinterlock recess and this released configuration allows the trigger tomove from the second trigger position to the first trigger position.Once the trigger is in the first trigger position, it is operable by theuser.

Preferably the priming assembly includes a priming actuator which isoperable from a first priming position to a second priming position andwhich includes an interlock recess; and the interlock includes a lockingmember which is able to enter the interlock recess when the primingactuator in the second priming position to release the interlock andallow the dispensing assembly to be operated.

The fluid may be a medical fluid. The fluid may be a liquid or a gel.The fluid may aid in the recovery or the comfort of the patient. Thefluid may have a viscosity similar to water at room temperature. Thefluid may have a higher viscosity than water at room temperature. Thefluid may be a pharmaceutical agent, hemostatic solution, wound-healingagent, analgesic, anti-adhesive, adhesive, irrigation fluid or coolingfluid. The fluid may include an anesthetic, an antibiotic in fluid form,a growth factor, suspended stem cells, chondrocytes, other biologicallyactive substances such as extra-cellular matrix, includingproteoglycans, glycosaminoglycan (GAG), chondroitin sulfate, or anantihemorragic.

The fluid may be a bone cement.

The fluid may be an adhesive. The adhesive may be a collagen-basedadhesive, a hydrogel, an albumin-based compound, a cyanoacrylate or afibrin.

The fluid may be a cyanoacrylate adhesive. The cyanoacrylate adhesivemay have a viscosity similar to water at room temperature.

In another embodiment, the fluid may be a fibrin adhesive. The fibrinadhesive may be a binary mixture in which two inactive precursor fluidsare mixed to form the active fibrin adhesive. The dispensing assemblymay comprise a first dispensing chamber for the first precursor fluidand a second dispensing chamber for the second precursor fluid. Thedispensing assembly may include a first plunger for the first dispensingchamber and a second plunger for the second dispensing chamber. Thefirst and second plungers may be advanced by a common plunger driveassembly. A mixing chamber may be located between the first and seconddispensing chambers and the dispensing shaft. The first and secondprecursor fluids may mix in the mixing chamber to form the active fibrinadhesive before moving into the dispensing shaft.

To ensure sterility and prolong shelf-life, a medical fluid may bestored in a sealed glass container. The container may be a glassampoule. If the fluid to be used in the surgical instrument of thepresent invention is stored in a sealed glass container, the surgicalinstrument may include a transfer assembly as described herein. Thetransfer assembly may enable the transfer of the fluid from the sealedglass container to the dispensing chamber. The fluid may be acyanoacrylate adhesive which is stored in a sealed glass container. Thecyanoacrylate adhesive may be stored in a sealed glass container toprevent contact with moisture which may cause the cyanoacrylate adhesiveto polymerise.

In another embodiment, the fluid may be stored initially in thedispensing chamber. In this embodiment, a transfer assembly may not berequired.

The surgical instrument may include a container in which the fluid isstored before the surgical instrument is used. The container may be aglass ampoule. The fluid may be transferred to the dispensing chamber bya transfer assembly. The transfer assembly may include a containerholder which holds the container. The container holder may include afilter. The apertures of the filter may be sized to allow the fluid topass but to retain any fragments of the container which are producedwhen the container is opened.

To release the fluid, the container may be opened. If the container is asealed glass container this may result in glass fragments beingproduced. The transfer assembly may comprise a filter to retain anyglass fragments produced in opening the sealed glass container. Anadvantage of this configuration is that it ensures that fluid which istransferred to the dispensing chamber is free of glass fragments.

The dispensing chamber may be attached to the transfer assembly.

The transfer assembly may be operable to open the container and transferthe fluid from the opened container to the dispensing chamber before thepriming assembly is operated.

The transfer assembly may be moveably mounted to the housing. Thetransfer assembly may pivot with respect to the housing. The transferassembly may be moveable between a first transfer position, a secondtransfer position and a third transfer position.

Movement of the transfer assembly from the first transfer position tothe second transfer position may cause the container to be opened torelease the fluid. The container may be opened by a projection on thetransfer assembly being pushed into the container. When the container isa glass ampoule, this will break open the ampoule. Any containerfragments created by the opening of the container will be retained bythe filter.

The container may be made of a frangible material. An example of afrangible material is glass. The container may be a frangible container.

The container may be made of a material which during deformation tendsto break up into fragments, rather than deforming plastically andremaining in one piece.

A polymer sleeve may at least partially surround the container. Thepolymer sleeve may be a PTFE sleeve. When the container is opened, thepolymer sleeve may prevent the fluid from spilling out of the containerholder.

The projection may be pushed into the container by relative movement ofthe container holder with respect to the projection. The transferassembly may include a breaker section which is moveable with regard toa holder section. The projection may be located on the breaker sectionand the container holder may attached to the holder section. When thetransfer assembly is moved from the first transfer position to thesecond transfer position, the holder section may move relative to thebreaker section. For example, the breaker section may be moveablyretained on the housing so that it cannot move as far as the holdersection. In this way, moving the holder section to its maximum extentwill move the holder section relative to the breaker section.

Once the fluid is released from the container, it may be directed to thedispensing chamber. A valve may be positioned between the container andthe dispensing chamber. The valve may comprise an outer valve body andan inner valve member. The valve may be a plug valve. The valve membermay be a cylinder with a cylindrical surface and axial ends. The valvebody may be annular and encircle the valve member. The valve member maybe attached to the housing at its axial ends and the valve body may beattached to the transfer assembly. In this way the valve member may actas a pivot around which the valve body and transfer assembly rotateswhen the transfer assembly moves between the first transfer position,second transfer position and third transfer position. This use of thevalve member as a pivot for the transfer assembly may advantageouslyreduce the number of components required in the surgical instrument.

A transfer channel may be defined by the valve member. When the valvemember is a cylinder, the transfer channel may be a channel on itscylindrical surface. The valve body may define a container holderopening which is in fluid communication with the container holder. Thevalve body may define a dispensing chamber opening which is in fluidcommunication with the dispensing chamber.

The valve member may further define a dispensing channel. The dispensingchannel may be a diametrical channel through the valve member.

When the transfer assembly is in the first transfer position, thetransfer channel may not be aligned with the container holder openingand the dispensing chamber opening. When the transfer assembly is in thesecond transfer position, the transfer channel may be aligned with thecontainer holder opening and the dispensing chamber opening to provide afluid path between the container holder opening and the dispensingchamber opening. In this way, fluid released from the container may flowfrom the container holder to the dispensing chamber when the transferassembly is in the second transfer position.

Before the surgical instrument is used, the sealing disc may be locatedat a distal end of the dispensing chamber. To draw the released fluidthrough the transfer channel from the container holder when the transferassembly is in the second transfer position, the sealing disc may beretracted proximally in the dispensing chamber. A pull member may beattached to the sealing disc to allow the user to retract the sealingdisc. When the transfer assembly is in the first transfer position, thepull member may be restrained from movement by the housing. When thetransfer assembly is moved from the first transfer position to thesecond transfer position, the pull member may move above the housing sothat it is no longer restrained.

Once all the fluid has been drawn into the dispensing chamber and thesealing disc is fully retracted, the pull member may disengage from thesealing disc. The pull member may comprise two fingers which engage arecess on the sealing disc so that the sealing disc may be retracted.The recess may be in the form of a through-hole. The fingers may beretained in the recess by the inner surface of the dispensing chamber.At its proximal end, the dispensing chamber may define two slots whichallow the fingers to disengage from the recess when the sealing disc isfully retracted. In this way, the pull member is disengaged andseparated from the dispensing chamber and may be discarded.

After the pull member is discarded, the sealing disc may be fullyretracted and the dispensing chamber contains the fluid to be dispensed.The transfer assembly may then be moved to the third transfer position.To reach the third transfer position, the transfer assembly may bepivoted about the valve member until the dispensing chamber opening isaligned with the dispensing channel. When the transfer assembly is inthe third transfer position, the sealing disc may be aligned with theplunger. The priming actuator may then be operated. When the primingactuator is operated from the first priming position to the secondpriming position, the plunger may advance the sealing disc distallywithin the dispensing chamber and push the fluid through the dispensingchamber opening and the dispensing channel. The proximal end of thedispensing shaft may be received within the valve member and the throughbore may be connected to the dispensing channel. Therefore fluid pushedthrough the dispensing channel may travel distally along the throughbore and be dispensed from the dispensing opening at the distal end ofthe dispensing shaft.

If the fluid to be dispensed is not initially contained in a glassampoule, a transfer assembly may not be required. In an alternativeembodiment, the surgical instrument may be supplied initially with thefluid already present in the dispensing chamber and the plunger alignedwith the sealing disc in a configuration similar to the third transferposition. The valve will not be required and the dispensing chamberopening will be in fluid communication with the proximal end of thedispensing shaft.

The fluid may be dispensed in discrete doses. Each dose may be apredetermined amount of fluid. A single dose may be known as a delivery.Each delivery may be of a predetermined volume. The dimensions of thedispensing chamber and plunger may be configured so that advancement ofthe plunger by a set distance dispenses the predetermined volume.

The predetermined volume of a delivery may be up to 50 mm³. Thepredetermined delivery volume may be from 10 mm³ to 40 mm³. Preferablythe predetermined delivery volume is from 20 mm³ to 30 mm³, morepreferably the predetermined delivery volume is approximately 25 mm³.

If the predetermined delivery volume is approximately 25 mm³ and theinternal diameter of the dispensing chamber is 7 mm, the plunger willadvance approximately 0.65 mm for each separate delivery of fluid.

The surgical instrument may be capable of dispensing a predeterminednumber of deliveries. The predetermined number of deliveries may be upto 50 deliveries. Preferably the predetermined number of deliveries isfrom 20 to 50 deliveries, more preferably from 30 to 40 deliveries. Thepredetermined number of deliveries may be 35 deliveries.

After the dispensing actuator has been operated for a number of timesequal to the predetermined number of deliveries, a hard stop on thedispensing assembly may prevent the dispensing actuator from beingoperated again. Preferably the hard stop feature prevents furtheroperation of the trigger after the trigger has been operated apredetermined number of times.

Preferably the hard stop is provided by a stop projection on the plungerdrive assembly engaging the housing. The stop projection may be locatedin a slot on the housing. The slot may be in an exterior surface of thehousing so that the stop projection is visible to the user of thesurgical instrument. The stop projection may advance in the slot as theplunger advances the sealing disc in the dispensing chamber. The hardstop may be provided by the stop projection reaching an end of the slot.The slot may be located so that the stop projection reaches the end ofthe slot when the predetermined number of deliveries is reached.

By being visible to the user, the relative position of the stopprojection in the slot may advantageously indicate the number ofdeliveries the surgical instrument has made. An indicator or scale maybe marked on the housing to allow the user to judge the number ofdeliveries more accurately. For example, if the stop projection islocated at a first end of the slot initially and reaches the second endof the slot when the predetermined number of deliveries is reached, thenif the stop projection is in the middle of the slot, approximately halfof the predetermined number of deliveries have been made.

The surgical instrument may be suitable for use in a minimally invasivesurgical procedure. The surgical instrument may be suitable for herniamesh fixation. The surgical instrument may be a hernia mesh fixationdevice.

When the surgical instrument is a hernia mesh fixation device, the fluidmay be a cyanoacrylate adhesive for securing a hernia mesh in place atthe operative site in the human or animal body. The hernia mesh may besecured in place by a number of deliveries of adhesive from the surgicalinstrument. Each delivery of adhesive may have a similar function to asuture or tack. The hernia mesh may be secured in place by between 20and 30 deliveries of adhesive. The hernia mesh may be secured in placeby approximately 25 deliveries of adhesive.

An embodiment of the invention will now be described by way of exampleonly with reference to the accompanying drawings, in which likereference numerals indicate like parts and in which:

FIG. 1 is a view of the surgical instrument from the right hand side;

FIG. 2 is an exploded view of the surgical instrument from above theright hand side;

FIG. 3 is a view inside the housing of the surgical instrument from theleft hand side;

FIG. 4 is an exploded view of the transfer assembly of the surgicalinstrument;

FIG. 5 is a view of the transfer assembly of the surgical instrumentfrom the right hand side;

FIG. 6 is a cross-section of FIG. 5 showing the valve of the transferassembly in the second transfer position;

FIG. 7 is a magnified view of a part of FIG. 6;

FIG. 8 is a view of the surgical instrument from the left hand side withthe pull member disengaged from the dispensing chamber;

FIG. 9 is a view of the surgical instrument from the left hand side withthe transfer assembly in the third transfer position;

FIG. 10 is a similar view to FIG. 9 with the left hand side of thehousing removed;

FIG. 11 is a cross-section from the right hand side showing the valve ofthe transfer assembly in the third transfer position;

FIG. 12 is a view of the priming assembly from the left hand side;

FIG. 13 is an exploded view of FIG. 12;

FIG. 14 is a cross-section of the surgical instrument from the righthand side showing the priming assembly in the first priming position;

FIG. 15 is a cross-section of the surgical instrument from the righthand side showing the priming assembly in the second priming position;

FIG. 16 is an exploded view of the dispensing assembly from the righthand side;

FIG. 17A is a view of the trigger gear wheel from the right hand side;

FIG. 17B is a view of the trigger gear wheel from the left hand side;

FIG. 18A is a view of the trigger from above the right hand side;

FIG. 18B is a view of the trigger from the left hand side;

As shown in FIG. 1, the surgical instrument 10 comprises a housing 20and a dispensing shaft 30. The housing 20 comprises a handle 22 whichallows the surgical instrument 10 to be gripped in one hand to allowone-handed operation of the surgical instrument 10. The housing 20 alsocomprises a body 24. The dispensing shaft 30 extends from the body 24.The housing 20 has a ‘pistol’ configuration in which the handle 22extends from the body 24 in a similar configuration to a pistol handleextending from a pistol barrel.

As shown in FIGS. 1 and 2, the dispensing shaft 30 is elongate and has aproximal end 31 and a distal end 32. The proximal end 31 of thedispensing shaft 30 is received within the housing 20 and the distal end32 defines a dispensing opening 33 for dispensing the fluid 12. Thefluid 12 is shown in FIGS. 7 and 14. The dispensing shaft has alongitudinal axis 34 which defines a proximo-distal axis for thesurgical instrument 10. The proximo-distal axis is oriented so that thedistal direction is generally towards the distal end 32 of thedispensing shaft 30 and the proximal direction is generally away fromthe distal end 32.

As shown in FIG. 7, the dispensing shaft 30 comprises an inner tube 35and an outer tube 36. The inner tube 35 defines a through bore 37 whichallows the fluid 12 to pass along the dispensing shaft 30. The outertube 36 is made of metal and the inner tube 35 is made of PTFE for lowfriction to assist the movement of the fluid 12 along the through bore37 by reducing shear stress.

The fluid 12 is a cyanoacrylate adhesive with a viscosity similar towater at room temperature. To ensure its sterility, the fluid 12 isstored in a sealed glass container 42 before the surgical instrument 10is used.

As shown in FIGS. 4 to 11, the surgical instrument 10 include a transferassembly 40 which enables transfer of the fluid 12 from the container 42to a dispensing chamber 82. The dispensing chamber 82 is attached to thetransfer assembly 40.

The transfer assembly 40 is moveably mounted to the housing 20. Thetransfer assembly is moveable between a first transfer position (shownin FIGS. 3, 6 and 7), a second transfer position (not shown in theFigures) and a third transfer position (shown in FIGS. 9, 10 and 11).

The transfer assembly includes a container holder 44 which holds thecontainer 42. The container holder includes a filter 46. The aperturesof the filter 46 are sized to allow the fluid 12 to pass through thefilter but to retain any fragments of the container 42 which areproduced when the container 42 is opened. A PTFE sleeve 43 partiallysurrounds the container 42. When the container 42 is opened, the PTFEsleeve 43 prevents the fluid 12 from spilling out of the containerholder 44.

Movement of the transfer assembly 40 from the first transfer position tothe second transfer position causes the container 42 to be opened by aprojection 48 on the transfer assembly 40 being pushed into thecontainer 42 to break the wall of the container 42. Any glass fragmentscreated by the opening of the container 42 will be retained by thefilter 46.

The projection 48 is pushed into the container 42 by relative movementof the container holder 44 with respect to the projection 48. Thetransfer assembly 40 includes a breaker section 50 which is moveablewith regard to a holder section 52. The projection 48 is located on thebreaker section 50 and the container holder 44 is attached to the holdersection 52.

In the first transfer position (as shown in FIGS. 3 and 6) the transferassembly 40 is at an angle of approximately 25° to the longitudinal axis34 of the dispensing shaft 30. When the transfer assembly 40 is movedfrom the first transfer position to the second transfer position, theholder section 52 is moved to an angle of approximately 35° to thelongitudinal axis 34. The breaker section 50 is retained by theengagement of a hook member 49 with a catch 21 on the housing 20 (shownin FIG. 16) so that it cannot move further than 25° to the longitudinalaxis 34. In this way, moving the holder section 52 to its maximum extentof approximately 35° will move the holder section 52 relative to thebreaker section 50 and will cause the projection 18 to break open thecontainer 42 and release the fluid 12.

Once the fluid 12 is released from the container 42, it is directed tothe dispensing chamber 82. As shown in FIGS. 6, 7 and 11, a valve 120 ispositioned between the container 42 and the dispensing chamber 82.

The valve 120 comprises an outer valve body 122 and an inner valvemember 124. The valve member 124 is a cylinder with a cylindricalsurface and axial ends. The valve body 122 is annular and encircles thevalve member 124. The valve member 124 is attached to the housing 20 atits axial ends and the valve body 122 is attached to the transferassembly 40. In this way the valve member 124 acts as a pivot aroundwhich the valve body 122 and transfer assembly 40 rotates when thetransfer assembly 40 moves between the first transfer position (see FIG.6), second transfer position and third transfer position (see FIG. 11).

A transfer channel 126 is defined by the valve member 124 as a channelon its cylindrical surface. The valve member 124 further defines adispensing channel 128 a diametrical channel through the valve member124.

The valve body 122 defines a container holder opening 130 which is influid communication with the container holder 44. The valve body 122also defines a dispensing chamber opening 132 which is in fluidcommunication with the dispensing chamber 82.

When the transfer assembly 40 is in the second transfer position, thetransfer channel 126 is aligned with the container holder opening 130and the dispensing chamber opening 132 to provide a fluid path betweenthe container holder opening 130 and the dispensing chamber opening 132.In this way, fluid 12 released from the container 42 may flow from thecontainer holder 44 to the dispensing chamber 82 when the transferassembly 40 is in the second transfer position.

Before the surgical instrument 10 is used, a sealing disc 108 is locatedat a distal end of the dispensing chamber 82. To draw the released fluid12 through the transfer channel 126 from the container holder 44 whenthe transfer assembly 40 is in the second transfer position, the sealingdisc 108 is retracted proximally in the dispensing chamber 82. A pullmember 54 is releasably attached to the sealing disc 108 to allow theuser to retract the sealing disc 108. As shown in FIG. 3, when thetransfer assembly 40 is in the first transfer position, the pull member54 is restrained from movement by the housing 20. When the transferassembly 40 is moved from the first transfer position to the secondtransfer position and the holder section 52 is moved to an angle ofapproximately 35° to the longitudinal axis 34, the pull member 54 movesabove the housing 20 so that it is no longer restrained.

Once all the fluid 12 has been drawn into the dispensing chamber 82 andthe sealing disc 108 is fully retracted, the pull member 54 disengagesfrom the sealing disc 108. The pull member comprises two fingers 56which engage a recess 110 on the sealing disc 108 so that the sealingdisc 108 may be retracted. The recess 110 is in the form of athrough-hole. The fingers 56 may be retained in the recess 110 by theinner surface 83 of the dispensing chamber 82. At its proximal end, thedispensing chamber defines two slots 81 (shown in FIG. 8) which allowthe fingers 56 to disengage from the recess 110 when the sealing disc108 is fully retracted. In this way, the pull member 54 is disengagedand separated from the dispensing chamber 82 (as shown in FIG. 8) and isthen discarded.

After the pull member 54 is discarded, the sealing disc 108 is fullyretracted and the dispensing chamber 82 contains the fluid 12 to bedispensed. The transfer assembly 40 may then be moved to the thirdtransfer position as shown in FIGS. 9 to 11. To reach the third transferposition, the transfer assembly 40 is pivoted about the valve member 124until the dispensing chamber opening 132 is aligned with the dispensingchannel 128 as shown in FIG. 11.

When the transfer assembly 40 is in the third transfer position, thesealing disc 108 is aligned with a plunger 84 as shown in FIG. 14.

As shown in FIGS. 12 to 16, the surgical instrument 10 further comprisesa priming assembly 60. The priming assembly 60 includes a primingactuator 62 which is operable to drive the priming assembly 60. Thepriming actuator 62 is rotatably mounted to a proximal end of thehousing 20. The priming actuator 62 is rotatable from a first primingposition shown in FIG. 14 to a second priming position shown in FIG. 15.

The priming assembly 60 includes a safety element which is moveable froman engaged position to a disengaged position and which prevent thepriming assembly 60 from being operated when it is in the engagedposition. The safety element is in the form of a pull tab 64 attached tothe priming actuator 62. In its engaged position (as shown in FIG. 14)the pull tab 64 engages a recess 28 on the housing 20 to prevent thepriming actuator 62 from being operated. The pull tab 64 is separablefrom the priming actuator 62 so that in its disengaged position, thepull tab 64 is separated from the priming actuator 62 to allow thepriming actuator 62 to be operated.

When the priming actuator 62 is rotated from the first priming positionto the second priming position, a plunger 84 advances and pushes thesealing disc 108 distally within the dispensing chamber 82 to push thefluid 12 through the dispensing chamber opening 132 and the dispensingchannel 128. The proximal end 31 of the dispensing shaft 30 is receivedwithin the valve member 124 and the through bore 37 is connected to thedispensing channel 128. Therefore fluid 12 pushed through the dispensingchannel 128 may travel distally along the through bore 37 and bedispensed from the dispensing opening 33 at the distal end 32 of thedispensing shaft 30.

Rotation of the priming actuator 62 from the first priming position tothe second priming position rotates a priming cap 66 with an internalscrew thread 65. The priming cap 66 is linearly moveable with respect tothe priming actuator 62 by the engagement of a spline feature 67 on thepriming cap 66 with a groove 63 on the priming actuator 62. The internalscrew thread 65 on the priming cap 66 engages a complementary screwthread 87 mounted on a plunger drive assembly 86. The priming cap 66 isconnected to a proximal end 78 of the plunger 84. In this way, rotationof the priming actuator 62 causes the internal screw thread 65 on thepriming cap 66 to advance along the complementary screw thread 87 on theplunger drive assembly 86. Since the plunger 84 is connected to thepriming cap 66, the plunger 84 will advance distally with respect to theplunger drive assembly 86 as shown in FIGS. 14 and 15. The advancementof the plunger 84 primes the through bore 37 of the dispensing shaft 30with fluid 12 by advancing the sealing disc 108 in the dispensingchamber 82 and urging the fluid 12 out of the dispensing chamber 82.

The priming assembly 60 includes an interlock 70 as shown in FIGS. 12,14 and 15. The interlock 70 is moveable from a locked configuration inwhich it prevents the dispensing assembly 80 from being operated to areleased configuration in which the dispensing assembly 80 is operable.The interlock 70 is only moveable to the released configuration once thepriming actuator 62 is in the second priming position. An advantage ofthe interlock 70 is that accidental operation of the dispensing assembly80 is not possible until the priming assembly 60 has been operated andthe priming actuator 62 is in the second priming position.

As shown in FIGS. 12 and 13, the interlock 70 includes a locking member72. The locking member is elongate and is slidably mounted in thehousing 20 to contact a locking formation 106 on the dispensing assembly80 (see FIGS. 14 and 15) and to contact the priming actuator 62. Whenthe priming actuator 62 is in the first priming position and theinterlock 70 is in the locked configuration, the locking member 72 isunable to move and locks the trigger 94 in the second trigger positionby contact with the locking formation 106.

The priming actuator 62 includes an interlock recess 74 positioned sothat when the priming actuator 62 is in the second priming position, theinterlock recess 74 is aligned with the locking member 72 to allow thelocking member 72 to move into the interlock recess 74. The spring 96exerts a force on the trigger 94 which causes the locking formation 106to move the locking member 72 into the interlock recess 74 and thisreleased configuration allows the trigger 94 to move from the secondtrigger position to the first trigger position. Once the trigger 94 isin the first trigger position, it is operable by the user.

As shown in FIGS. 11, 14 and 15, the dispensing assembly 80 comprises adispensing chamber 82. The fluid 12 is held in the dispensing chamber 82before it is moved into the dispensing shaft 30. The elongate plunger 84is positioned to advance or retract within the dispensing chamber 82.When the plunger 84 is advanced within the dispensing chamber 82, thefluid 12 is urged out of the dispensing chamber 82 and into the throughbore 37 of the dispensing shaft 30. The plunger advances within thedispensing chamber 82 in a distal direction. Fluid 12 urged out of thedispensing chamber 82 enters the through bore 37 of at the proximal end31 of the dispensing shaft 30.

The plunger 84 has a distal end 79 which abuts against a sealing disc108 which engages the internal surface 83 of the dispensing chamber 82to form a seal. Advancement of the plunger 84 advances the sealing disc108 within the dispensing chamber 82.

As shown in FIGS. 13, 14 and 15, the plunger 84 is connected to aplunger drive assembly 86 which includes a rack 88 and pinion gear wheel90. The pinion gear wheel 90 is mounted within the housing 20. Turningthe pinion gear wheel 90 engages the rack 88 to advance or retract theplunger 84. When the plunger 84 advances the sealing disc 108 is pushedalong the dispensing chamber 82. Retraction of the plunger 84 will notcause the sealing disc 108 to move because the plunger 84 abuts thesealing disc 108 instead of being physically connected to the sealingdisc 108.

The dispensing assembly 80 comprises a dispensing actuator 92 which isoperable to drive the dispensing assembly 80. The dispensing actuator 92is connected by an intermediate gear wheel 104 to the pinion gear wheel90 of the plunger drive assembly 86.

As shown in FIGS. 14, 15 and 16 the dispensing actuator 92 includes areciprocable trigger 94 mounted to the housing 20 between the handle 22and the body 24 of the housing 20. The trigger 94 is operable by auser's finger from a first trigger position to a second triggerposition. The trigger 94 is biased by a spring 96 to return to the firsttrigger position when the user's finger is released at the secondtrigger position. The spring 96 is attached to the housing 20 at a firstend 95 and attached to the dispensing actuator 92 at a second end 97.

As shown in FIGS. 18A and 18B, a pawl 98 is moulded into the trigger 94and a ratchet 100 is connected to a trigger gear wheel 102. When thetrigger 94 is moved from the first trigger position to the secondtrigger position the pawl 98 engages the ratchet 100 to turn the triggergear wheel 102. When the trigger 94 is moved from the second triggerposition to the first trigger position the pawl 98 and ratchet 100disengage so that the trigger gear wheel 102 does not turn.

As shown in FIGS. 14 and 15, turning the trigger gear wheel 102 willturn the intermediate gear wheel 104 to turn the pinion gear wheel 90 toadvance the plunger 84. The relative sizes of the trigger gear wheel102, intermediate gear wheel 104 and pinion gear wheel 90 are chosen toprovide an overall gear ratio between the trigger gear wheel 102 and thepinion gear wheel 90 of 4 to 1. Therefore a 10° rotation of the trigger94 results in a 2.5° rotation of the pinion gear wheel 90. The size ofthe pinion gear wheel 90 is chosen to advance the rack 88 by apredetermined amount when the trigger 94 is operated from the firsttrigger position to the second trigger position. This will cause theplunger 84 to advance by a predetermined amount to dispense apredetermined volume of the fluid 12 from the dispensing opening 33 ofthe surgical instrument 10.

As shown in FIGS. 17A and 17B an indexing wheel 101 is attached to thetrigger gear wheel 102. The indexing wheel 101 enables the movement ofthe trigger 94 between the first trigger position and the second triggerposition to be indexed. The indexing wheel 101 includes indentations 99on its circumference which engage an indexing formation 103 on thehousing 20 (see FIG. 16) to provide the indexing. The engagement of theindentations 99 with the indexing formation 103 also provides anadditional frictional force on the ratchet 100 to assist the trigger 94to move from the second trigger position to the first trigger positionwithout moving the ratchet 100.

The surgical instrument 10 dispenses the fluid 12 in discrete doses. Asingle dose is known as a delivery and each delivery is a predeterminedvolume of fluid 12. The internal diameter of the inner surface 83 of thedispensing chamber 82 is chosen to be 7 mm so that advancement of theplunger 84 by a set distance of 0.65 mm will dispense a predeterminedvolume of approximately 25 mm³.

The surgical instrument 10 is capable of dispensing a predeterminednumber of deliveries which is 35 deliveries. After the dispensingactuator 92 has been operated 35 times, a hard stop on the dispensingassembly 80 prevents the dispensing actuator 92 from being operatedagain. The hard stop is provided by a stop projection 112 on the plungerdrive assembly 86 (as shown in FIG. 13) engaging the housing 20.

As shown in FIGS. 9 and 16, the stop projection 112 is moveable within aslot 26 on the housing 20. The slot 26 is in an exterior surface of thehousing 20 so that the stop projection 112 is visible to the user of thesurgical instrument 10. The stop projection 112 advances in the slot 26as the plunger 84 advances the sealing disc 108 in the dispensingchamber 82. The hard stop is provided by the stop projection 112reaching a distal end of the slot 26. The slot 26 is located so that thestop projection 112 reaches the distal end of the slot 26 when thepredetermined number of 35 deliveries is reached. By being visible tothe user, the relative position of the stop projection 112 in the slotmay provide a visual indication of the number of deliveries the surgicalinstrument 10 has made.

Use of the surgical instrument 10 in a hernia mesh fixation procedurewill now be described.

The fluid 12 is a cyanoacrylate adhesive suitable for securing a herniamesh in place at the operative site in the human or animal body. Thehernia mesh is secured in place by a number of deliveries of adhesivefrom the surgical instrument 10. Each delivery of adhesive has a similarfunction to a suture or tack. The hernia mesh is secured in place byapproximately 25 deliveries of adhesive. Since the predetermined maximumnumber of deliveries of the device is 35 deliveries, there areapproximately 10 extra deliveries of adhesive available for the surgeonto use as necessary. The surgeon may use some of these extra deliveriesfor closure of the peritoneum if appropriate.

The detailed sequence of the steps for using the surgical instrument 10is as follows. In this description, it is assumed that a scrub nurse anda surgeon will be present during the procedure but the surgicalinstrument 10 may also be prepared and used by a single person.

The surgical instrument 10 is provided in sterile packaging with thetransfer assembly 40 in the first transfer position at an angle of 25°to the longitudinal axis 34 of the dispensing shaft 30. The scrub nurseremoves the surgical instrument 10 from the packaging and moves thetransfer assembly 40 to the second transfer position at an angle of 35°to break the container 42 within the container holder 44. The move tothe second transfer position aligns the dispensing chamber 82 and thecontainer holder 44 with the transfer channel 126 on the valve 120. Nextthe scrub nurse retracts the sealing disc 108 in the dispensing chamber82 by pulling the pull member 54 to draw the adhesive fluid 12 into thedispensing chamber 82. The pull member 54 self-detaches at the end ofits travel and is discarded.

The scrub nurse then moves the transfer assembly 40 to the thirdtransfer position (as shown in FIGS. 9, 10 and 11) which moves thedispensing chamber 82 from alignment with the transfer channel 126 ofthe valve 120 to alignment with the dispensing channel 128.

At this stage, the transfer sequence has been completed and the primingsequence can be started. To start the priming sequence the scrub nurseremoves the safety element 64 which releases the priming actuator 62.Next the scrub nurse rotates the priming actuator 62 which advances theplunger 84 to push the sealing disc 108 forward distally in thedispensing chamber 82 which in turn pushes adhesive fluid 12 through thedispensing channel 128 of the valve 120 and along the through bore 37 ofthe dispensing shaft 30 to near the dispensing opening 33 of thesurgical instrument 10. Once the priming actuator 62 has been rotated320° from the first priming position to the second priming position, thelocking member 72 of the interlock 70 is pushed backwards into theinterlock recess 74 on the priming actuator 62 by the force of thespring 96 on the dispensing actuator 92. This causes the trigger 94 tobe released to the first trigger position which completes the primingsequence and the surgical instrument 10 is now ready for use.

The scrub nurse hands the surgical instrument 10 to the surgeon to use.When the surgeon uses a finger to pull the trigger 94 from the firsttrigger position to the second trigger position, the plunger driveassembly 86 advances the plunger 84 to make a delivery of fluid adhesive12 from the dispensing opening 33. When the surgeon releases the trigger94 the dispensing actuator 92 is rotated by the spring 96 from thesecond trigger position back to the first trigger position without theratchet 100 rotating, ensuring that the plunger 84 remains stationary.The Surgeon uses up to 25 deliveries of adhesive fluid 12 to attach thehernia mesh in the desired position.

1. A surgical instrument for dispensing a fluid comprising: a housing; adispensing shaft which is elongate and which has a proximal end and adistal end, wherein the proximal end of the dispensing shaft is receivedin the housing and the distal end defines a dispensing opening fordispensing the fluid and the dispensing shaft includes a through borewhich extends along the dispensing shaft from the proximal end to thedispensing opening at the distal end; a dispensing assembly connected tothe housing which includes a dispensing chamber which holds the fluidbefore it is dispensed, wherein the dispensing chamber is in fluidcommunication with the through bore of the dispensing shaft and thedispensing assembly is operable to move the fluid from the dispensingchamber along the through bore and dispense the fluid from thedispensing opening; and a priming assembly connected to the housingwhich is operable to move an amount of the fluid into the through boreof the dispensing shaft to prime the through bore with the fluid beforethe dispensing assembly is operated.
 2. A surgical instrument as claimedin claim 1 wherein the priming assembly and the dispensing assembly forman interlock so that the dispensing assembly cannot be operated untilthe priming assembly has been operated.
 3. A surgical instrument asclaimed in claim 2 wherein the priming assembly comprises: a primingactuator which is operable from a first priming position to a secondpriming position and which includes an interlock recess; and theinterlock includes a locking member which is able to enter the interlockrecess when the priming actuator in the second priming position torelease the interlock and allow the dispensing assembly to be operated.4. A surgical instrument as claimed in claim 1 wherein the dispensingassembly includes a trigger mounted to the housing which is operable todispense a predetermined amount of fluid each time the trigger isoperated.
 5. A surgical instrument as claimed in claim 4 wherein thepredetermined amount of fluid is a predetermined delivery volume of from20 mm³ to 30 mm³.
 6. A surgical instrument as claimed in claim 4 furthercomprising a hard stop for preventing further operation of the triggerafter the trigger has been operated a predetermined number of times. 7.A surgical instrument as claimed in claim 6 wherein the hard stop isprovided by a stop projection on the dispensing assembly engaging thehousing to prevent further operation of the dispensing assembly.
 8. Asurgical instrument as claimed in claim 1 wherein the priming assemblyincludes a safety element which is moveable from an engaged position toa disengaged position, wherein when safety element is in the engagedposition it prevents the priming assembly from being operated and whenthe safety element is in the disengaged position the priming assembly isoperable.
 9. A surgical instrument as claimed in claim 1 which includesa plunger which abuts against a sealing disc which is slidably mountedwithin the dispensing chamber, wherein operation of the dispensingassembly causes the plunger to advance the sealing disc within thedispensing chamber to urge the fluid out of the dispensing chamber andalong the through bore in the dispensing shaft.
 10. A surgicalinstrument as claimed in claim 1 which includes: a container in whichthe fluid is stored before the surgical instrument is used; and atransfer assembly connected to the housing which is operable to open thecontainer and transfer the fluid from the opened container to thedispensing chamber before the priming assembly is operated.
 11. Asurgical instrument as claimed in claim 10 wherein the container issealed and the transfer assembly is moveable from a first transferposition to a second transfer position to open the sealed container torelease the fluid.
 12. A surgical instrument as claimed in claim 11wherein the container is a sealed glass container and the transferassembly includes a filter for separating glass fragments produced whenthe sealed glass container is opened from the fluid which is releasedfrom the opened container.
 13. A surgical instrument as claimed in claim11 wherein the transfer assembly is moveable to a third transferposition and the transfer assembly includes a valve which is positionedbetween the container and the dispensing chamber wherein in the secondtransfer position the valve allows the fluid to flow from the containerinto the dispensing chamber and wherein in the third transfer positionthe valve allows the fluid to flow from the dispensing chamber into thedispensing shaft.
 14. A surgical instrument as claimed in claim 1wherein the fluid is an adhesive.
 15. A surgical instrument as claimedin claim 14 wherein the adhesive is a cyanoacrylate adhesive.